1. Different types of lights have been used to increase the growth of various plants. Our experiment tested whether LED or fluorescent lights produce plants with longer root length and higher germination rates. Fluorescent lights, which emit heat, consume more energy, and emit a more intense light are typically used in laboratories. LED lights, which consume 10% less energy than fluorescent lights, can last for many more years that fluorescent lights, but are more expensive. Are the LED lights really worth the cost? We performed an root growth experiment to find out. Effects of LED and Fluorescent Lights on Root Growth of Arabidopsis Kevin O’Quinn, Mesha Arant, Jordan Ball, and T.J. White Department of Biology, Wofford College, Spartanburg, SC 29303 Introduction Materials and Methods Summary & Status of Hypotheses Hypothesis 1.Germination rates will be higher in plants grown under the LED lights. 2.Root length will be greater in plants grown under the LED lights. Materials 48 Arabidopsis seeds(Ecotype: Columbia) Petri dishes with 0.8% Agar Fluorescent and LED Growing Lights Methods 0.8% Agar was placed into 6 slanted Petri dishes. Eight seeds were placed in each dish along the thin edge of the agar to reduce crowding. Dishes were sealed and placed in a vertical position under the LED and Fluorescent lights at a distance of 34cm. On a photoperiod of 16 hours light and 8 hours dark. Each seed was individually identified. Germination rates and root length were measured weekly for two weeks. Dishes were placed on a scanner and the images were analyzed with ImageJ software; root lengths were measured. Discussion 1. Germination was not affected by light source. 2. Root growth was greater under fluorescent lights. Our results did not support our hypotheses. Root Length of Plants under Fluorescent and LED lights Our experiment showed that fluorescent lights produced plants with longer roots than the LED light panel. Of course, one of the drawbacks of fluorescent lights is that it requires more energy than LED lights to operate. This may be contribute to higher operational costs, but may have aided in the difference in root lengths between the fluorescent and LED lights. Because the fluorescent lights used more energy, perhaps that they emitted more energy. This extra energy could have given the plants grown under fluorescent lights the advantage. In comparison, because the LED lights used less energy, they emit less energy; this could have contributed to the shorter root length. Since the LED lights were less intense, we should have moved them closer to the plants in order to have the same intensity as the fluorescent lights. In the future, it would be best to figure out the distance from the lights to the plants in order to equalize the intensity being exposed to the plants. The circles show the average root length and the error bars show 95% confidence intervals. Root growth from week 1 to week 2 was greater for plants grown under Fluorescent lights than for plants under LED lights (p=0.002, Chi Square F df=1,36 =1.8. ) We did not graph the growth from Week 0 to Week 1 because during that interval growoth was likely produced by energy from the seed’s endosperm and not from the light. Explanation of Graph Acknowledgements Germination Rate The germination rate, not shown, was not statistically different for seeds under fluorescent and LED light (Chi-square (dF=1)=0.137; p=.712). We thank G.R.. Davis for assistance with experimental design, Ab Abercrombie for help with statistical analysis, and A. Steadman and T. Player for helpful comments. Example of Petri Dishes